Pressure dependence of the large-polaron transport in anatase TiO2 single crystals
1 Laboratory of Physics of Complex Matter Physics, Ecole Polytechnique Fédérale de Lausanne CH-1015 Lausanne, Switzerland
2 Institute of Physics - 11001 Belgrade, Serbia
Received: 21 April 2012
Accepted: 6 August 2012
We have measured the pressure and temperature dependences of the resistivity and the thermoelectric power of anatase, TiO2. The resistivity varies with T3 at high temperatures, and its absolute value is in the 1 Ωcm range. Below 60 K, the resistivity is activated. Most surprisingly, the activation energy shows non-monotonic pressure dependence. The thermoelectric power has a very high value and its temperature dependence resembles that of polaronic materials. We suggest a large polaronic model to describe the temperature and pressure dependence of the two transport coefficients.
PACS: 71.38.-k – Polarons and electron-phonon interactions / 71.55.-i – Impurity and defect levels / 71.20.Nr – Semiconductor compounds
© EPLA, 2012